Sealing Carb To Scoop

old neighbor has a 69 Lemans with a 13:1 455 in it. we built a fresh air system, like a Thunderbolts for it. He had 4 headlights so we took the high beams out, did some cutting on the core support and used a factory style air filter housing with a a second "snorkel" welded to it. In the heat of the summer in AZ his car picked up a little over a tenth.